1. Field of the Invention
This invention is related to the field of diamond drilling equipment, especially diamond core drilling in concrete with a tool which can operate at different angles. The diamond core drilling equipment of the invention is employed to drill holes in concrete surfaces.
2. Description of the Prior Art
A prior art patent search was conducted and a list of patents which appeared to us to be most pertinent to the invention follows.
WO 89/1081 Nov. 16, 1989 Depres shows a hole saw guided by a pilot drill. When the motion of the drill is reversed and the hole saw prevented to rotate, the hole saw pulls back, thus freeing the carrot. Though this system has the potential to be used to drill larger holes in concrete, it provides no means to bring cutting fluid to the surface, because all parts are rotating simultaneously. PA0 U.S. Pat. No. 4,620,823 Nov. 4, 1986 Hillestad illustrates a portable milling tool using a collet at the end of a shaft as a wedging means to secure and centre the tool. Although the advance of the cutting tool is commanded by a nut moving along a threaded shaft, the system is quite complex due to internal gear mechanism and would prove costly and cumbersome for larger applications such as diamond core drilling in concrete. Also no means are provided to bring cutting fluid to the work surface. PA0 U.S. Pat. No. 4,911,253 Mar. 27, 1990 Cliche describes a core water and mud collector tool for use by a carrotting drill. Though the system provides water to the cutting area, it needs external means to do so. At least a second operator with a hose is needed to spray water on the core bit. Also there is no means for precisely centering the hole on the concrete surface and controlling the rate of advance of the bit. PA0 BE 493209 May 2, 1950 Victor Products illustrates a system in which the advance of the drill is controlled by threads engaging the bit's spiral wall. An implant, in which the bit screws itself, must be installed on the surface in which the hole is to pierced. The implant must first be inserted in a shallow hole where ears are pushed outwardly to restrain any retrieving movement while piercing. This system has three drawbacks: first the advance rate is dependent upon the rotation rate of the bit; secondly, the size of the hole is limited by the size of the implant, meaning that a different implant is needed for each hole size; finally, no means of feeding the cutting area with fluid is provided. PA0 U.S. Pat. No. 4,902,174 Feb. 20, 1990 Thompson describes a system in which an external collar is used to secure and centre the piercing apparatus. A collar system of this type is impossible on flat surfaces. PA0 WO 83/02728 Aug. 18, 1983 TRI-TOOL describes a portable machine tool for preparing pipe ends as illustrated on front page of patent document. This system uses expandable wedging mandrel means for radially gripping the interior of a pipe; the tool feed drive is once again composed of a nut that pushes the tool 70 towards the work. In this case the nut 82 is turned via a gear mechanism which is practical for small scale such as pipe end applications, but which would be cumbersome for twelve inch diameter and over diamond core drilling. Also the twin horizontal ball bearing support would be costly to reproduce in large diameter applications. In such cross shaped tool arrangement, the use of central water feeding would be impractical. PA0 U.S. Pat. No. 3,825,362 Jul. 23, 1974 Hougen shows a cup shaped annular cutter for forming circular hole. The tool provides spring loaded means to center the carrotting bit, but none to support it. Still, there is no means of spraying cutting fluid. PA0 DE 3724-232-A Feb. 2, 1989 Fein shows a diamond core drill mounted on a pillar fixed to a base. Typical drilling equipment for this application employs an external support system for the hole saw. However this kind of system comprises many cantilever supports which make the system unstable and limited in power. Moreover, when tilted to be used at a certain angle --FIG. 5--, the fixation of the barrel forms a second cantilever, limitating even more the use of the capacities of the drill. Finally, the barrel diameter is limited to 12 inches. PA0 U.S. Pat. No. 306,477 Fuller, Oct. 14, 1884 provides central support for core bit via a bridge structure which could permit large diameter drilling but with large dimension arrangement. This method nowadays illustrated in FIG. 6 makes use of an external support bridge that supports the diamond bit. This arrangement permits the use of larger diamond bits but requires much larger working space, much larger than the drill bit diameter. PA0 WO 88/02290 Apr. 7, 1988 TRI-TOOL illustrates a mandrel assembly for a portable lathe. A blocking system 62 is used at the end of a shaft assembly 50 to secure and center the tool onto the work piece 38. The tool feed mechanism is comprised of a threaded shaft 32 for milling feeding 34 by turning handle 44. A manually tightened nut 90 pulls end 80 towards the block piece 62. The system does not have any capability to provide cutting fluid to the cutting apparatus, other than by external means.
While study of the prior art shows several inventions using means which could prove useful in diamond core drilling, none has a combination of means or capabilities of the invention herein described.